The estimated cost of hosting the 2012 Olympics was “entirely unrealistic” at the time of London’s bid, a report by the public spending watchdog says today.

The Public Accounts Committee accuses the Government of ignoring factors such as a contingency provision, tax obligations and security requirements that resulted in an “astonishing” increase in the budget from £4 billion to £9.3 billion within two years of winning the Games.

MPs also say that the Department for Culture, Media and Sport is guilty of wishful thinking in its prediction that the private sector would contribute £738 million towards venues and infrastructure.